JPS6018319A - Processing and molding method of thermoplastic stampable sheet - Google Patents

Abstract

PURPOSE:To obtain a sheetlike molded article having a smooth surface existing no sink and having a reinforcing protrusion, by joining and unifying heat softening sheets of thermoplastic stampable sheets by making press molding of them in two processes within a press molding die. CONSTITUTION:A predetermined quantity of a heat softening blank 15 of a thermoplastic stampable sheet is placed on a recessed part 11a of the top of a central protrusion of a bottom force 11 and then a to force 10 and the bottom force 11 are closed. At this time the blank is heated at a temperature higher than the melting point or the softening point, and the force are kept at a temperature lower than those. When press molding is done between both the forces, the inside of the recessed part 11a is filled completely with the softened blank 15 and the remainder of the same is made into a part of a sheetlike part 14. Both the forces are opened after completion of the press molding and cool curing in this first process. Then both a premolded resin 15a and a heat softening blank 16 are unified by joining and adhering closely to each other by a method wherein as a second process a quantity of the heat softening blank 16 to be necessitated to obtain a required thickness of the sheetlike part is placed on the premolded resin 15a and the press molding is done by closing the top force 10 onto the bottom force 11 again.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a processing and molding method for obtaining molded articles of desired shapes from thermoplastic methane bubble seams.

A thermoplastic methane bubble sheet is a sheet made of relatively long glass fibers formed into a mat shape as a reinforcing material.
This was soaked in molten thermoplastic resin and pressed to form a sheet.

The thermoplastic methane bubble sheets 1 to 1 are trimmed according to the size of the molded product to be obtained (hereinafter, the cut material before molding is referred to as a blank), and the blank is cut into thermoplastic synthetic resin in a heating furnace. Below the softening temperature of -I.

(hereinafter referred to as a heat-softened blank), and the heated blank was then press-molded in a matte metal die mold that was kept at a temperature below the softening temperature of the thermoplastic resin, and then cooled and solidified. By doing so, the desired shape can also be formed into a molded body.

This method has the characteristic that the molding cycle can be made faster compared to conventional compression molding methods for thermosetting reinforced resins. In addition, the molded product obtained by compression molding the thermoplastic stamped pulp sheets 1 to 1 has tensile and bending strength, impact strength, and
In addition, the elastic modulus is human, and the durability against vibration fatigue is high.

For this reason, it is most suitable as a material for 1LI functional parts, and is often used, for example, as exterior panels for automobiles.
The exterior panels for automobiles had a curved shape. 19(
Anti-molded products are used. In this case, jiff is applied to a thin plate-like molded product with a curved surface like an exterior panel
! Ribs or bosses (
It is common to cover the surface of the molded product (hereinafter referred to as the reinforcing protrusion) by integrally forming it.

However, during molding, a support plate-like molded product having reinforcing protrusions on the back side produces sink marks 4 (dents, see Figure 1) on the surface corresponding to the reinforcing protrusions 3. The disadvantage is that smoothness is lost and the appearance is significantly impaired. The occurrence of sink marks is due to the difference in wall thickness between the part where the reinforcing protrusion 3 is formed and the part 2 where it is not formed. During cooling and solidification at 15G), the amount of resin contraction in the thickness direction is:
When the shrinkage rate is constant, it changes in proportion to the cross-sectional thickness. Therefore, as shown in FIG. 1, the shrinkage Φ of the thick wall portion on which the reinforcing protrusion 3 is formed also extends to the thin flat surface portion 2, and as a result, the reinforcing protrusion 3 The surface portion corresponding to 9 is in a concave state as shown in the figure.

This occurrence of sink marks is a common problem in synthetic resin molding, but in order to solve this problem, mainly in the 0.1 molding method, the resin is heated under pressure.
By avoiding foaming inside the resin in the molten FAi+ state, molding can be carried out while retaining air bubbles to reduce the shrinkage M that occurs during one round of cold N, or (.L, A predetermined part of the mold on which the four parts for forming the reinforcing protrusions are not formed is formed into a concave shape. One person is using methods such as posting.

On the other hand, in the processing and molding of thermoplastic methane bubble sheets, the blank sheet is heated and softened under normal pressure and then molded under pressure, so sufficient foaming cannot be achieved under normal pressure. Even if heat molding is possible, most of the bubbles will collapse and disappear, so there is little effect on preventing sink marks.Also, thermoplastic molding is the method of forming recesses on the mold surface that corresponds to the areas where sink marks occur. Although it can be applied to methane bubble sear 1, it is difficult to modify the mold and is not reliable in preventing sink marks, resulting in low yield. This has the disadvantage of increasing stress (deterioration, mold production).

This invention was made in view of the conventional problems as described above, and its purpose is to form a plate-shaped molded product on the right side of a reinforcing protrusion made of thermoplastic methane bubble seams 1 to 9. Therefore, it is possible to easily and reliably produce a thermoplastic stampable sheet with a smooth surface without sink marks, and it also allows the use of existing molds and does not require any modification to the mold. The purpose is to provide a method.

In order to achieve the above object, the method according to the present invention is a method for forming a thin plate molded product having reinforcing protrusions formed from a thermoplastic stamp sheet 1 (including the following steps). It is characterized by containing.

That is, (a) Heat-softened resin (blank) of a thermoplastic methane bubble sheet is placed above the four reinforcing protrusion molding parts formed on one of the pair of press molding molds in a sufficient length to swirl the recesses. a first step of placing the mold, closing the mold, and performing pressure molding; (b) placing a newly heat-softened thermoplastic stampanorcy 1 on the molded product obtained in the first step; The second step consists of joining and integrating both blanks by placing the blanks on the holder and performing pressure forming again, The bonding and integration with the heat-softened resin placed on the molded body in the second step is performed directly or indirectly through a porous sheet. There is.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

First, FIG. 2, FIG. 3, FIG. 4, and FIG. 5 are explanatory diagrams of a molding procedure based on an embodiment of the molding method of the present invention.

In Figures 2 to 5, J3 is shown, 10 is an upper mold (cavity type), 11 is a lower mold (core type), and the lower mold 11 has a curved central protrusion (core part) with ribs on the top surface The upper mold 10 has a recess 11a for molding a reinforcing protrusion (or boss portion), and has a curved surface 12 on its inner wall that matches the upper surface of the central protrusion of the lower mold.

FIGS. 2 and 3 show the first step, which is a preforming step for forming a portion of the reinforcing projection 13 and the plate-like portion 14. FIG. First, a predetermined amount of heat-softened blanks 15 of the thermoplastic methane bubble seams 1 to 1 is placed on the four parts 11a of the upper surface of the central part of the lower mold 11, and the upper mold 10 and the lower mold 11
and close. At this point, the blank is heated above the Mitt point or softening temperature of the resin, and the mold is held at a temperature below that temperature. When pressure molding is performed between the two molds, the softened blank 15 is heated to a temperature above the Mitt point or softening temperature of the resin. As shown in the figure, the inside of the recess 11a is completely filled, and the remaining amount becomes a part of the plate-like part 14.

After completing the pressure molding and cooling solidification in the first step, the mold is opened and the next step is moved to the second step.

FIGS. 4 and 5 show the second step, in which the thickness of the plate-shaped portion to be covered is set to 1! Place the heat-softened blank '1G in the amount required for "I" on the preformed resin 15a, and 1J and upper mold 10 1 Tomoe 1 11
When it is closed and pressure molded, both resins are bonded and integrated.

When the preformed resin is cooled and solidified in the first step, sink marks (not shown) are formed on the surface of the resin at positions corresponding to the reinforcing protrusions 13. The heat-softened blank 16 added to the process is the first
Surface of the molded product in the process - 1 (When pressure molded, the softened blank 16 undergoes molding under approximately uniform plate thickness conditions, so shrinkage during cooling and assimilation is reduced. The amount is uniform over the entire surface and no shrinkage occurs.

6, 7, 8 and 9 show other embodiments of the molding method of the present invention, and the same parts as the embodiment shown in FIGS. 2 to 5 are designated by the same reference numerals. Although the explanation of the duplicate structure and effect will be omitted, the bonding between the preformed resin 15a that was applied in the first process and the heat-softened blank 16 that is added in the second process is further improved. This embodiment differs from the above embodiment in that both resins are integrally bonded via a breathable porous sheet 17 to ensure strength.

FIG. 6 and FIG. 7 show the first step, which is a preforming step similar to the first step in the above embodiment, and is a heat softening step placed on the lower mold 11. A breathable porous sheet 17 whose area covers the entire upper surface of the central protrusion of the lower die 11 is placed on the blank 15. Upper mold 10 from above
When opened and pressurized, preforming is performed as shown in Figure 7, and as the resin cools and solidifies, a preformed product in which a part of the porous sheet 17 is embedded and fixed in the resin 15a is formed. can get.

FIGS. 8 and 9 show the 21st culm, and at about 2-L, a predetermined amount of heat-softened blanks 16 are placed ( Pressure molding is performed again.

However, unlike the above embodiment, a porous sheet 17 is buried and fixed in the upper surface of the preformed resin 15a and is exposed on the surface of the resin. 1, that is, the porous sheet 17, which is firmly bonded and integrated with the image molding resin 15a, both resins bite into the uneven shape, resulting in the anchoring effect of the sheet 1~ (both j
3 are strongly physically connected.

Examples of the breathable porous sheets 1 to 17 include open-cell plus deck sheets, two-knit woven fabrics made of various fibers, unwoven fabrics, glass fiber mats, or paper-like fibers. In addition to these 6, L) various breathable porous sheets 1
He was hired and became the 1st! luru9, also methane bubble sea 1~
Examples of thermoplastic 1'1 resins for forming 1'1 include polyethylene, bolyb-11 pyrene, borisdyrene, polyvinyl monide, ΔIJ S 4DJ resin, nylon 6, nylon 66, polyethylene terephthalate 1, polybutylene terephthalate, etc. Examples of fibers suitable for reinforcing the thermoplastic methane bubble sear 1- include glass fibers, carbon fibers, and polyamide fibers.

Next, specific examples based on the molding method of the present invention will be shown.

Example 1 (1) Thermoplastic methane bubble seams 1 to 1 were made of 665 mm % nylon and 35 wt % glass mat, and had a thickness of 3.5 mm in which glass pine 1 was sufficiently impregnated with resin.

(2) As shown in Fig. 10, the lower die has a central protrusion with a flat surface of 20011m x 150111m and a height of 2511In, and a width of 2.5n+n+ and a depth of 10IIIm for rib forming. Three grooves were cut parallel to the short side at intervals of 501 mm and 111 mm. On the other hand, the bottom surface of the upper mold is 200mm x 100mm.
A cavity mold with a depth of 25 mm was used.

(3) 120mm nylon stampable sheet
Trimmed and cut to a size of
Heat the heated blank and place it in the medium heat section of the mold at a temperature of 120°C so that the long side is in the direction of the long side of the mold, immediately close the mold, and reduce the pressure to 301~. was added and held for 30 seconds. Looking at the mold, a plate with a thickness of 1 mm is formed, and the -1-curve of the rib part has a width of 2 mm.
Some linear sink marks (indentations) were observed.

(4) Place the heated zonal ink of the same method as in the first step on top of this, close the mold again, apply pressure of 301-mm, hold for 30 seconds, then mold 1 Hearing this, I took out a 2.5mm thick flat plate with glue.

The surface was smooth with no sink marks.

Example 2 (1) The configurations of the thermoplastic methane bubble sear 1 and the pine boot die mold are the same as in the above-mentioned "Example 1".

(2) A nonwoven fabric made of polyethylene terephthalate, (2) (J7!IOg/W2. Appearance thickness: 0.35 mm) was used as a breathable porous sheet.

(3) - 120m of Bouillon stampable sheet
The trim cut to a size of m x 100'mm is heated to an internal temperature of 280℃ with a far infrared heater, softened, and wetted with an Iζ heated blank. I placed the blank sheet so that the long side was facing up. On top of that, apply the above nonwoven fabric to 200 +nmx
The mold was cut to a size of 15 Q ++ on, and the mold was tightened so as to cover the entire surface of the central protrusion of the mold, and a pressure of 30 tons was applied and held for 30 seconds. Looking at the mold, a flat plate with a thickness of 111n+glue was formed.

Non-woven fabric was embedded in the surface, leaving part of the feather-like material exposed.

(4) Place a heated blank with the same dimensions as the heated blank in the first step in the same manner as this, close the mold again, and
After applying a pressure of 01 to -U and holding it for 30 seconds, a flat plate with ribs having a thickness of 2.5 mm was taken out from the mold. The surface was smooth with no sink marks. Also, the first
The bond between the process molded product and the second process molded product was very strong.

As described above, according to the method of the present invention, in the second step, a heat-softened blank is directly applied to the molded article having a reinforcing protrusion formed in the ULL step, or Since the molded body is indirectly joined and integrated through the molded sheets 1 to 1, sink marks that are generated on the surface due to the difference in wall thickness of the molded body are removed.

Although it can be reliably prevented, existing molds can be used and modifications to the mold are not necessary.
The thermoplastic stampable sheet can be formed at low cost.

[Brief explanation of the drawing]

Figure 1 was obtained using the conventional molding method! FIGS. 2 to 5 are explanatory diagrams of the sink spot occurrence area of the molded product, and are 1 explanatory diagrams showing the steps of an embodiment of the method according to the present invention, and FIGS. 1 culm, FIGS. 4 and 5 show the second step, and FIG. 6 to FIG. 9 are explanatory views showing steps T of another embodiment of the method according to the present invention. , FIG. 6 and FIG. 7 show the first step, FIG. 8 and FIG. 9 show the second step, and FIG. 10 shows a mold according to a specific embodiment of the present invention. 174 explanatory diagram of 10... Upper mold 11 Lower mold 11a .・・・・・・・・・・・・Reinforcement ￥Original part 15,”1
6... Heat softening blank (heat softening resin) 17...
・・・・・・・・・Breathable porous sheet! l:I:+
T Applicant Ube Nitto Kasei Co., Ltd. Agent Patent Attorney
-Kensuke Iro

Claims (1)

[Claims] A method of molding a molded article having a desired shape with reinforcing protrusions 811 by pressure-forming a thermoplastic-stambable sheet with a pair of press-forming dies and then cooling and solidifying the sheet, the method comprising: Place enough heat-softened resin of thermoplastic methane bubble sear 1 to 1 in a can above the four molding parts of the reinforcing protrusion formed on one side of the mold so as not to fill the recess, and then close the mold. A first step of performing pressure molding with
A second process is performed in which a thermoplastic methane bubble sheet resin that has been newly heat-softened is placed on the molded body obtained in the first culm, and pressure molding is performed again to bond and integrate both resins. The molded product obtained in the first step and the heat-softened resin placed on the molded product in the second step are joined and integrated directly or by using a breathable porous sheet. A method for processing and forming a thermoplastic stampable sheet, characterized in that the process is performed indirectly through a process.